1. Field of the Invention
This invention concerns an apparatus for filling flexible bulk containers. The contents of the container are relatively slowly raised and then relatively rapidly impacted or dropped quickly to densify the contents thereof. Alternatively or in addition, the apparatus provides for compressing the container to increase the density of the contents. The method and apparatus hereof enables the container contents to be continuously weighed during densification and compaction.
2. Description of the Prior Art
One method of storing and distributing bulk materials involves the use of flexible intermediate bulk containers, hereinafter referred to as FIBCs. FIBCs are typically used to contain dry or semi-moist flowable bulk material therein and are provided with a woven polypropylene, normally air permeable fabric outer layer. The FIBCs are typically rectangular in configuration and are provided with four lifting loops at the top corners. An inlet spout for filling the contents of the FIBC is located at the center of the top wall thereof and configured to fit around a material inlet of a filling machine. The FIBC may also be provided with an air-tight polyethylene liner. Many different types of material may be contained by these large bag-like FIBCs such as, e.g., cement, kaolinite, talc, and plastic pellets. Thus, it may be appreciated that FIBCs can be used to carry a wide variety of loose, substantially dry bulk material, and typically the FIBCs have a capacity of one to three tons.
The material contained in the FIBCs is typically sold by weight, and thus during filling of the FIBCs with the bulk material, there is a need to weigh the contents to ensure an accurate amount of bulk material is received within the bag. Concomitantly, there is a need to ensure that each bag contains a maximum volume of the material, not only for efficient utilization of the space within the FIBC, but also to enable each FIBC to stack more easily with greater stability and to ensure efficient utilization of warehouse and transport vehicle space.
To this end, apparatus has been developed to densify the contents of an FIBC. That is to say, densifying apparatus has been developed to "pre-settle" the contents of the FIBC and thus minimize wasted space in the interstices between the particles of the bulk material. These prior art devices have often rapidly agitated or vibrated the contents of the container. While this accomplished densification to a certain degree, it also was largely inefficient in that it tended to re-suspend or "re-loosen" the contents during the rapid upward movement of the container.
Another problem which has been encountered is the inability to obtain optimum densification of particularly light, fluffy materials, such as, e.g., kaolinite. While conventional densification has moderately improved the density of such materials at or near the bottom of the container, the lightweight material at the top of the container has remained loose. There has thus developed a need to further densify containers carrying such loose, fluffy materials therein.
There thus remains a need for an apparatus which will more efficiently densify the contents of the FIBC, which will accomplish densification more quickly, and which will reduce the overall time needed to fill, weigh and densify the FIBC so that the entire process may be expedited, thus improving productivity.